Gender-related expression of TRα and TRβ in the protandrous black porgy, Acanthopagrus schlegeli, during sex change processes

We cloned the thyroid hormone receptor α (TRα) and β (TRβ) cDNAs from the ovaries of the protandrous black porgy and compared the expression levels of TRα and TRβ mRNA during the sex change in black porgy. We observed that the TRα mRNA by quantitative real-time PCR and protein levels by Western blot were highest in the mature ovaries. Additionally, TRβ mRNA levels were only expressed highly in the mature ovaries when compared to any other gonadal stages. Then, we injected gonadotropin-releasing hormone analogue (GnRHa) to know the effects on TRs mRNA in immature black porgy. Injection with GnRHa resulted in a significant increase in TRα level while significantly reducing TRβ level after 12 h. We concluded that TRα was related in testicular development as well as ovarian development and TRβ was only affect to ovarian development in black porgy. These results will provide a framework for better understanding of the role of TRs during sex change processes in this fish.